Starter drive for combustion engines

ABSTRACT

A pinion is provided, and a drive-transmitting hollow shaft. An outer element is annular and concentric to the shaft, having a flange connected therewith. An inner annular element is surrounded by the outer element and connected with the pinion, and a plurality of curved cam tracks on the inner circumference of the outer element are angularly offset about and eccentric to the axis of the same, defining with the inner body confined spaces which converge in circumferential direction. An annular disc is stationarily received between these elements and provided with axial projections each having a surface elongated in circumferential direction, and rolling bodies are accommodated in the confined spaces. Pressure springs are also accommodated in the respective confined spaces abutting and guided by the surfaces and also abutting against the rolling bodies, urging the latter circumferentially in the direction of convergence of the spaces.

United States Patent Barthruff et al.

[451 Sept. 19, 1972 [541 STARTER DRIVE FOR COMBUSTION ENGINES Inventors: Otto Barthruff, Stuttgart; Walter Ruhle, Korntal, both of Germany Robert Bosch GmbH, Stuttgart, Germany Filed: Dec. 31, 1970 Appl. No.: 103,134

[73] Assignee:

[30] Foreign Application Priority Data US. Cl ..74/6, 192/45 Int. Cl ..F02n 15/00 Field of Search ..74/7, 7 A, 7 B, 6; 192/45 [56] References Cited UNITED STATES PATENTS 4/1934 Sorensen 192/45 6/1 960 Kochendorfer ..74/6 4/1962 Blinder ..192/45 Primary Examiner-Milton Kaufman Attorney-Michael S. Striker [57] ABSTRACT A pinion is provided, and a drive-transmitting hollow shaft. An outer element is annular and concentric to the shaft, having a flange connected therewith. An inner annular element is surrounded by the outer element and connected with the pinion, and a plurality of curved cam tracks on the inner circumference of the outer element are angularly offset about and eccentric to the axis of the same, defining with the inner body confined spaces which converge in circumferential direction. An annular disc is stationarily received between these elements and provided with axial projections each having a surface elongated in circumferential direction, and rolling bodies are accommodated in the confined spaces. Pressure springs are also accommodated in the respective confined spaces abutting and guided by the surfaces and also abutting against the rolling bodies, urging the latter circumferentially in the direction of convergence of the spaces.

8 Claims, 4 Drawing Figures PATENTEUSEP 1 9 m2 sum-1 0F 2 INVENTOR kru'nuFF.

gal; ii! at"! mare;

ATTORNEY PATENTEHSEP 19 m2 SHEET 2 [IF 2 INVENTOR 0770 EARTH F n Mark! 2000: 1-104 I l'fi'b ATTORNEY STARTER DRIVE FOR COMBUSTION ENGINES BACKGROUND OF THE INVENTION The present invention relates generally to starter drives for combustion engines, and more particularly to an improved starter drive of a simpler and less expensive construction than heretofore known.

It is already known to provide starter drives having a pinion, an inner annular body connected with the pinion, and an outer annular body connected via a flange with a hollow drive shaft. The outer annular body has on its inner circumference angularly offset curved cam tracks which extend eccentrically with reference to the shaft axis and define with the inner annular body confined spaces which taper in wedgeshaped configuration circumferentially and which accommodate rolling bodies pressed towards the narrower end of the respective space by circumferentially extending springs which abut against axial projections of an annular disc maintained immovably between the two annular bodies.

The prior art provides for the annular disc to be made of sheet steel and to be maintained in engagement with the outer annular body by having its outer circumference configurated so as to mate with the cam tracks in the inner circumference of the outer annular body. The axial projections against which the pressure springs abut, are stamped out of the plane of the annular disc and bent at right angles to the same. The pressure springs have a rectangular cross section and are each guided in a sleeve of U-shaped configuration whose open side through which the respective spring is insertedabuts against the annular disc. The sleeves and rolling bodies are held against axial displacement within the outer annular body by two semi-circular profiles which close the open side of the outer annular body. I

This prior art construction is operable for its intended purpose; however, the rectangular-cross section springs are diflicult to produce and therefore very expensive, not to mention the fact that this prior art construction requires a rather large number of individual components and is therefore difficult and expensive to produce and to assemble.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to provide an improved starter drive of the type generally under discussion, which is not possessed of the disadvantages outlined above.

More particularly, it is an object of the invention to provide such an improved starter drive which can be very rapidly and economically manufactured and assembled.

A concomitant object of the invention is to provide such an improved starter drive which is capable of utilizing conventional circular-cross section pressure springs and has a minimum number of components.

In pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides in a starter drive for combustion engines which, briefly stated, comprises a pinion, a drivetransmitting hollow shaft, an outer annular element concentric to and having a flange connected with said shaft, and an inner annular element surrounded by the outer element and connected with the pinion. A plurality of curved cam tracks is provided on the inner circumference of the outer element angularly offset about and eccentric to the axis of the same, and which defines with the inner body confined spaces converging in circumferential direction. An annular disc is stationarily received between the elements and provided with a plurality of axial projections each having a surface elongated in circumferential direction and rolling bodies are accommodated in the confined spaces. Pressure springs are also accommodated in the respective confined spaces abutting and guided by the aforementioned surfaces, and also abutting against the rolling bodies, urging the latter circumferentially in the direction of convergence of the aforementioned spaces.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side view, partially sectioned, illustrating an embodiment of the invention;

FIG. 2 is a section taken on line [1-11 of FIG. 1;

FIG. 3 is a view on an enlarged scale, showing a detail of FIG. 1; and

FIG. 4 is a section taken on line IV-IV of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail, it will be seen that the exemplary drive illustrated in the embodiment in FIGS. 1-4 comprises a pinion 10 which, after the drive is assembled, will be tumably and axially shiftably mounted on the shaft of a non-illustrated starter drive motor. The motor itself forms no part of the present invention, and is therefore not shown. In any case, such motors are conventional.

The pinion 10 has a cylindrical shaft 11 constituting the inner annular body of an overrunning coupling 12. As shown in FIG. 1, the shaft of the non-illustrated starter drive motor is provided with a steep-pitch external thread on one of its sections, and a follower, identified with reference numeral 14 and being of one piece constituted of sleeve 14a, flange 14b, and annular body 140, is provided with a corresponding internal thread 13 which meshes with the steep-pitch thread so that the follower 14 can become threadingly displaced longitudinally of the shaft.

The annular body constitutes the outer annular element of the overrunning coupling 12, and a two-part sleeve 15 is provided on the sleeve 14a. A non-illustrated lever of a non-illustrated energizing relay engages the sleeve 15, and-it is pointed out that the lever and the relay are not illustrated because they are conventional and do not in themselves form a part-of the present invention, nor are they needed for an understanding of the invention. A spring 16 abuts against the sleeve 15 and the flange 14b.

The annular body 140 surrounds the shaft 11 of the pinion and is provided on its inner circumference with a plurality of curved cam tracks 17 which are shown in FIG. 2, and which extend eccentrically to the axis of the coupling and are equi-angularly offset in circumferential direction. Rollers 18 and pressure springs 19 are interposed between the annular body 14c and the shaft 11 of the pinion, in such a manner that each of the circumferential extending pressure springs 19 presses the associated roller 18 into the narrow portion of the confined circumferentially tapering space defined between the respective eccentric cam tracks 17 and the outer surface of the shaft 1 l.

A two-part disc 20 closes the opening of the body 14c and thereby retains the rollers 18 and the pinion in the element 14 against axial displacement. A retaining ring or washer 21 in turn prevents the disc from axial displacement.

A plurality of axial projections 28 is provided which extend axially into the open side of the element 14 and against which the pressure springs 19 abut. The projections 28 are provided on an axial end face of an annular member 29 equi-angularly spaced with reference to one another and which annular element 29 is accommodated in the interior of the member 14 as shown particularly in FIG. 1. It abuts, as shown in'the drawing, against the flange 14b, as FIG. 3 shows most clearly, its outer circumference is configurated matingly with and in correspondence with the cam tracks 17 on the inner surface of the annular body 140. The projections 28 of the annular disc 29 (compare FIG. 4) abut against the disc 20 so that the annular element 29 is held in position without play.

As the drawing shows, the construction according to the present invention makes it possible to utilize pressure springs 19 which have a circular cross section and can also be produced simply and in conventional manner, as opposed to pressure springs having a rectangular cross section required in the prior art, and which are substantially more expensive. The pressure springs 19 engage the rollers 18 approximately centrally and are guided laterally by surfaces 30 from the base of the respective projections 28 on the annular element 29, as shown in FIG. 4.

It is highly advantageous to make the annular element 29 of synthetic plastic material, and more particularly to make it by injection molding because this permits this component to be made simply and inexpensively. The outer diameter of the element 29 is slightly greater than the inner diameter of the annular body 140 so that when the element 29 is pressed into the interior of the body 140 until it abuts against the flange 14b, it will be frictionally retained and received concentrically within said outer annular element 14c in tightly-fitted relationship therewith. During such insertion, the very small amount of excess material resulting from the slightly greater diameter of the element 29 versus the inner diameter of the element 140, is peeled off by the edge at the open side of the element 14c so that the element 29 is seated reliably and firmly.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a starter drive for combustion engines, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 7

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A starter drive for combustion engines, comprising a pinion; a drive-transmitting shaft; an outer annular element concentric to and having a flange connected with said shaft; an inner annular element surrounded by said outer element and connected with said pinion; a plurality of cam track portions on the inner circumference of said outer element angularly offset about and eccentric to the axis of the same, and defining with said inner element confined spaces converging in circumferential direction; an annular disk positioned between said elements and rigidly connected with said outer element and provided with a plurality of axial projections each having a surface elongated in axial direction; rolling bodies accommodated in said confined spaces; and pressure springs also accommodated in the respective confined spaces abutting and guided by said surfaces, and also abutting against said rolling bodies and urging the latter circumferentially in the direction of convergence of said spaces.

2. A starter drive as defined in claim 1, said disc and said axial projections being unitary with one another.

3. A starter drive as defined in claim 2, wherein said disc and axial projections consist at least predominantly of synthetic plastic material.

4. A starter drive as defined in claim 1, said annular disc having an outer circumference matingly corresponding to said inner circumference of said outer element.

5. A starter drive as defined in claim 4, wherein said annular disk is received concentrically within said outer annular element in tightly fitted relationship therewith.

6. A starter drive as defined in claim 1, wherein said pressure springs are cylindrical.

7. A starter drive as defined in claim 1, further comprising a ring-shaped washer extending across and closing the inner free opening of said outer annular element, and abutting against free endfaces of said axial projections.

8. A starter drive as defined in claim 1, said pressure springs being cylindrical springs and each being laterally supported by one of said surfaces. 

1. A starter drive for combustiOn engines, comprising a pinion; a drive-transmitting shaft; an outer annular element concentric to and having a flange connected with said shaft; an inner annular element surrounded by said outer element and connected with said pinion; a plurality of cam track portions on the inner circumference of said outer element angularly offset about and eccentric to the axis of the same, and defining with said inner element confined spaces converging in circumferential direction; an annular disk positioned between said elements and rigidly connected with said outer element and provided with a plurality of axial projections each having a surface elongated in axial direction; rolling bodies accommodated in said confined spaces; and pressure springs also accommodated in the respective confined spaces abutting and guided by said surfaces, and also abutting against said rolling bodies and urging the latter circumferentially in the direction of convergence of said spaces.
 2. A starter drive as defined in claim 1, said disc and said axial projections being unitary with one another.
 3. A starter drive as defined in claim 2, wherein said disc and axial projections consist at least predominantly of synthetic plastic material.
 4. A starter drive as defined in claim 1, said annular disc having an outer circumference matingly corresponding to said inner circumference of said outer element.
 5. A starter drive as defined in claim 4, wherein said annular disk is received concentrically within said outer annular element in tightly fitted relationship therewith.
 6. A starter drive as defined in claim 1, wherein said pressure springs are cylindrical.
 7. A starter drive as defined in claim 1, further comprising a ring-shaped washer extending across and closing the inner free opening of said outer annular element, and abutting against free endfaces of said axial projections.
 8. A starter drive as defined in claim 1, said pressure springs being cylindrical springs and each being laterally supported by one of said surfaces. 